Diverse plant assemblages store more carbon and are part of more productive ecosystems, but plant biodiversity is not usually incorporated into predictions of carbon futures. A new study in the journal Nature Communications, co-authored by Sarah Weiskopf (National CASC), Brian Miller (North Central), Toni Lyn Morelli (Northeast CASC), and partners, finds that future plant biodiversity loss could decrease carbon storage in land ecosystems.  

In their study, the researchers estimated the impact of biodiversity loss on carbon storage by using large-scale ecological modeling and data from decades of local-scale experiments that quantify the relationship between biodiversity and plant biomass – a good indicator of carbon storage. Combining these approaches allowed the researchers to predict how changes to plant biodiversity under two future climate and land-use scenarios might impact global carbon storage.  

First, the researchers considered a “global sustainability” scenario. This scenario describes a future in which humans successfully limit global warming to 2 degrees Celsius by the end of the century, achieving the goals set by the Paris Agreement. The model’s predictions for this scenario estimate that different ecoregions around the world could lose between 14.6-45.9% of plant species which could cause a loss of between 7.44-103.14 Pg (petagrams) of stored carbon. For context, it would take about 12.1 Pg of water to fill Lake Superior (one petagram of water equals one billion metric tons). 

Second, the researchers considered a “fossil-fueled development” scenario, which describes a future with high climate change, intermediate land-use change, and continued exploitation of fossil fuels. This scenario predicted a loss of between 36.9-46.2% of plant species across various ecoregions, resulting in a global loss of between 10.87-145.95 Pg of stored carbon. 

The IPCC estimates that human carbon emissions need to stay below 140 Pg to limit warming to 1.5 degrees Celsius, and below 310 Pg to limit warming to 2 degrees Celsius. The study’s upper estimates of carbon loss (103 Pg and 146 Pg) caused by biodiversity loss from the two future scenarios would make up a large percentage of the IPCC-set limits. But other factors like agricultural practices, permafrost thawing and changes to fire regimes are also expected to contribute to the loss of storage potential. Because most projections of future global carbon budgets do not account for the effect of biodiversity, they could be missing a significant source of carbon loss and overestimate the future carbon storage potential of terrestrial ecosystems. 

Overall, this study emphasizes the possibility of a self-reinforcing feedback loop, where climate change leads to greater biodiversity loss, which in turn increases carbon emissions to worsen climate change. The results from this CASC-supported study demonstrate how current management practices like expanding forest areas to improve carbon storage could be made more effective by also considering biodiversity conservation and restoration. 

The full citation for this paper is: Weiskopf, S.R., Isbell, F., Arce-Plata, M.I. et al. Biodiversity loss reduces global terrestrial carbon storage. Nature Communications, 15, 4354 (2024). https://doi.org/10.1038/s41467-024-47872-7